For a number of production lines, it is very important to be able to determine the weight either of the materials entering the process, or the products leaving the production line. This is for example true for a number of goods sold in supermarkets such as for example meat items, food items, pre-processed food stuffs, fish, etc.
For these reasons a number of systems have been developed in order to register the weight of items as they travel in the production facility, for example on conveyors. One such systems is known from EP 0440999 wherein a separate conveyor structure is arranged on a weight. As an item is transferred from one conveyor onto the weighing conveyor, the weighing unit will register the added weight placed on the conveyor belt, and thereby the weight of the item to be weighed.
This construction is relatively large as it is a self-standing unit, and furthermore the system from a hygienic point of view comprises a number of drawbacks as it is very difficult to clean these conveyor structures sufficiently in that the conveyor belt in the prior art is a closed surface conveyor belt.
Furthermore, the structure according to the prior art is suitable for one purpose only in that the weighing unit needs to be placed such that influences from the surroundings are completely isolated, and thereby have no effect on the conveyor, or the items placed on the conveyor.
From WO 9728072 a conveyor belt assembled from a plurality of substantially identical chain links is known. The links are provided with substantially rectangular notches along a first edge, which notches are arranged perpendicular to the intended travelling direction. The longer side of the rectangular notches are arranged parallel to the top surface of the links. On the edge opposite the first edge provided with notches, substantially circular recesses are provided. The cross dimensions of the recess corresponds to the length of the rectangle of the notches. The circular recess is furthermore provided with an opening allowing the shorter side of the rectangle on the notch to pass. By turning the connecting chain links such that their top surfaces are parallel, a pivotal coupling is established between the two adjacent chain links. A problem with this prior art construction is the fact that it requires a certain minimum construction height in that the construction of the notches as well as the receiving recesses requires relative dimensions in order to provide the required strength and in order to accommodate and guide the rectangular notches during assembly. These requirements result in a relatively robust and heavy construction.
Furthermore, endless conveyor belts of this type are typically arranged around wheels in either end of the conveying structure. Due to the rectangular shape of the notches and the size of the notch receiving recesses, a certain minimum diameter of the wheels is required such that the risk of disassembly of the chain links is avoided. The overall construction height of the conveying structure is therefore relatively high.
Other types of belts used for check weighing systems are illustrated in prior art documents EP 0283209 and GB 783056, wherein the structure is made from bending a wire or a thin strip of metal back and fourth, and arranging holes perpendicular to the travelling direction close to the front and rear edges of the bent wire. Thereafter, an identical bent wire or a thin strip of metal may be inserted such that the holes overlap and may be connected by a transverse rod. In this manner, a flexible and easily bendable conveyor belt is provided which is suitable for use in a check weighing system. This type of belt, however, comprises a number of disadvantages which the present invention sets out to alleviate. Among these disadvantages is the fact that especially when producing food stuffs, the large number of apertures and parts create a number of crevasses where matter may become stuck. This matter may give rise to contamination, or other unhygienic conditions. Furthermore, the construction of the conveyor belt itself makes it very difficult to thoroughly clean the belt structure such that a high hygienic standard may be maintained, and furthermore such that the flexibility of the belt, and thereby the correctness of the weighing procedure, may be assured.